MONITORING AND QUANTIFYING HEAT LOSS FROM SIGNIFICANT GEOTHERMAL AREAS VIA REMOTE SENSING

Abstract

Accurate assessment of natural heat loss from significant
geothermal areas is essential for providing data to improve
reservoir simulation and model calibration. Uncertainty in
this parameter can lead to large uncertainty in resource
assessments and in predictions of sustainable utilisation
rates. Monitoring of surface heat-loss changes during
production is equally important for history-matching of
reservoir models and for assessment of environmental
effects. New methods are under development for making
better use of thermal infrared imagery from the newly
launched Landsat-8 satellite, which has improved in quality
and frequency (in tandem with Landsat-7). Along with
ground-truth measurements, and high-resolution air-borne
infrared surveys, these data are expected to achieve a longterm
improvement in the determination of natural and
induced changes in surface heat loss.
Issues currently being addressed to assist with better heat
flux estimates using remote sensing techniques include:
accounting for surface emissivity variations and ambient
(background) solar radiation; calibration against surface
temperatures of water-bodies; and using optimized
algorithms for atmospheric correction (split or mono
window). With respect to heat-loss assessment, issues
include: accounting for convective vapour loss; and dealing
with spatial resolution issues. Integration of imagery with
spot measurements of total heat-flux from areas of weakly
steaming ground is challenging. This paper summarizes
efforts to date in resolving these issues, and provides some
examples of heat-loss assessments from Karapiti thermal
area (Craters of the Moon), Wairakei, New Zealand